Synthesis of active high mannose-type lipoprotein lipase in human adipose tissues

Lipoprotein lipase (LPL) activity in the retroperitoneal adipose tissue of a patient with Gushing's syndrome and in the subcutaneous adipose tissue of a patient with aseptic necrosis of the femoral head was higher than that i n the corresponding tissues of the control subjects. The amount of [S-35]me thionine incorporated into LPL was also higher in these patients than in co ntrol subjects. However, the ratio of activity and amount of radioactivity in the LPL of patients was identical to that of control subjects, indicatin g that LPL synthesized in the adipose tissues of patients had a normal spec ific activity. LPL with M-r = 57 000 was composed of two types of subunits: one type was partially endo H-sensitive, yielding a product with M-r = 55 000, and the other was totally endo H-sensitive, yielding a product with M- r = 52 000. Both retroperitoneal and subcutaneous adipose tissues of contro l subjects contained nearly equal amounts of partially and totally endo H-s ensitive subunits. In the retroperitoneal adipose tissue of a patient with Gushing's syndrome, 8% of subunits were partially endo H-sensitive and 92% were totally endo H-sensitive. In the subcutaneous adipose tissue of a pati ent with aseptic necrosis of the femoral head, 21% of subunits were partial ly endo I-I-sensitive and 79% were totally endo H-sensitive. The 24-h treat ment of subcutaneous adipose tissue of a control subject with 1 mM 1-deoxym annojirimycin (dMM) caused the synthesis of active, but totally endo H-sens itive, LPL. Thus, in human adipose tissue, the processing of one oligosacch aride chain of an LPL subunit to a complex type chain in the trans Golgi wa s not necessary for the expression of activity. (C) 2001 Elsevier Science I reland Ltd. All rights reserved.